Swear word, literally “his mother’s.” Like “fuck,” the phrase has a sexual connotation, though it is less harsh than its English counterpart and has a broader range of uses. Like its English-language counterpart, it is versatile, changing its meaning depending on context. This term is often abbreviated WTF or TMD.

A very notable use of the phrase appeared in the July 26, 2011 edition of Hong Kong’s Apple Daily newspaper shortly after the Wenzhou train accident. The front page headline read, “Clearing the Tracks, Not Saving Lives; WTF!” (只要通车不要救人 他妈的!)